There is a substrate processing system having a processing chamber for forming an insulating film or a metal film for forming wiring or the like by CVD (Chemical Vapor Deposits) on a surface of a circular plate-shaped wafer as a substrate. In this substrate processing system, when a film is formed in a substantially circular shape on the wafer surface, it is preferable that the center of the wafer coincides with that of the film. However, a discrepancy of an actual film forming position (an actual film position where a film is formed by treatment) with respect to a reference film forming position (a target film position where a film should be formed) (hereinafter, referred to as a “film position discrepancy”) may be generated due to a discrepancy occurring during wafer transfer or due to a variation in plasma distribution in the processing chamber (see FIG. 6).
In order to correct the film position discrepancy, the position of the wafer on the mounting table is adjusted in the processing chamber. To be specific, when the film position is discrepant, the position of the wafer with respect to the plasma in the processing chamber is adjusted by adjusting the position of the wafer on the mounting table by using of a transfer arm (transfer unit) transferring the wafer.
Since the size of the film is smaller than that of the wafer, a non-film forming portion where a film is not formed on the wafer surface (see FIG. 6) is generated on the wafer surface. The film position discrepancy is calculated by measuring the width of the non-film forming portions in several locations of the wafer.
The width of the non-film forming portion of the wafer is measured by using a metallographic microscope after the wafer is unloaded from the substrate processing system by an operator. To be specific, the width is measured on a peripheral portion of the substrate at locations which are 90° apart in a circumference direction by using the metallographic microscope.
However, the measurement using a metallographic microscope is disadvantageous in that the wafer needs to be unloaded from the substrate processing system by an operator as described above and also in that the film position discrepancy calculated from the width of the non-film forming portion needs to be inputted to the substrate processing system by the operator. Besides, since an allowable film position discrepancy of about 0.2 mm the influence of measurement error can be large, so that the position of the wafer needs to be measured and adjusted repetitively. Namely, a considerable period of time is required to correct the film position discrepancy.